Conventional concrete materials are typically made of Portland cement, sand, stone and water. When water is mixed with the Portland cement, an exothermic reaction occurs.
Although conventional concrete is useful for many applications, the process for making concrete must be carefully controlled. Chemical ratios of the starting materials must be adhered to strictly. Precise quantities of water must be used, and controlled temperatures for curing are required. Furthermore, extreme care must be used when bonding conventional concrete to other structures. Such critical parameters increase costs, and result in relatively long process times for many applications.
Phosphate-containing ceramics have been proposed for encapsulating residual materials. U.S. Pat. Nos. 5,645,518, 5,830,815, 5,846,894 and 6,133,498 disclose phosphate ceramics which encapsulate various types of residual materials and contaminants such as heavy metals, asbestos, ash, lumber wastes, styrofoam, cellulose fibers, tires, textile wastes, and low-level radioactive waste. The residual materials act as fill materials which are encapsulated and do not participate in the chemical reaction of the product. Such processes use high-purity reagent grade dead burned MgO. The MgO requires further processing including calcining the MgO further to reduce its reactivity, requires additional buffers, such as oxides of boron to further control MgO reactivity, requires the use of hydroxides as an added buffer, and also requires pretreatment of the MgO by wash and acid wash techniques. Reagent grade fine powder forms of phosphates are required, and liquid phosphoric acid is used to initiate acid reactions in conjunction with the dry phosphate powders. These previous approaches require strict ratio control of the reagent grade MgO and phosphates. Chemical buffers are used to control reactivity of the precise formulas. Such precise chemical formulas are extremely sensitive to temperature during field implementation.
U.S. Pat. No. 5,002,610 discloses of the use of fiber additives to magnesium phosphate cements and non-reactive fill materials in order to achieve mechanical properties desirable for construction uses similar to those of Portland cement-based concrete.
U.S. Pat. No. 6,136,088 discloses the production of a cement and/or mortar based on the reactions of water, magnesium compounds, and potassium phosphate that utilize retardants such as boron oxide, polyphosphonic acid, carboxylic acid, hydroxycarbyloxylic acid, and salts of these acids. Additives such as silica, class F fly ash, talc, clay based sand, silica fume and mixtures of these materials are used as inert fillers.
The present invention has been developed in view of the foregoing, and to address other deficiencies of the prior art.